70 C20 750CFM Quadrajet Fuel Pressure 8psi

[CW4B]

Installing an SMI rebuilt Stage 1 Quadrajet 750CFM carb. I have a new mechanical fuel pump, not sure of the specs but supposedly correct one for year/make/model.

Carburetor instructions insist that fuel pressure should be 5 psi, 5.5 max.

Because I don't have fuel pressure gauge installed normally, I checked fuel pressure by disconnecting fuel line from carburetor and connecting it to a fuel gauge. I then cranked the engine over until fuel gauge showed a stable reading, and that's where I'm getting the 8psi.

Questions:
1) Does this method deliver an accurate reading for this purpose?
2) If no, how should I check fuel pressure?
3) If yes, what can I do to reduce pressue?

Thanks,